The best way to prevent more diseases from jumping from animals to humans is to stop deforestation and wildlife trading
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- Many of the world's deadliest diseases — including the novel coronavirus — came from animals.
- Experts in animal-to-human disease transmission say increased deforestation and wildlife trading are causing more and more of these zoonotic spillover events.
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Two new diseases have jumped from animals to humans every year, on average, over the last century. Some are mild, but others — like Ebola and HIV — are devastating.
Most experts now agree that Sars-CoV-2, the virus that causes COVID-19, came from bats, though we still don't know exactly how or when that happened. It's likely the coronavirus passed through an intermediary species before infecting people.
What scientists are sure about, however, is that due to widespread deforestation and a rampant global wildlife trade, humans are mixing with animals more often than ever in our history. The more those interactions occur, the more zoonotic spillover — the scientific term for animal viruses infecting humans — we're likely to see.
Peter Daszak, the president of EcoHealth Alliance, told NPR in April that his colleagues are "finding 1 to 7 million people exposed" to zoonotic viruses in Southeast Asia each year.
Currently, three out of every four emerging infectious diseases come from animals.
"We're going to encounter more of these diseases," Stuart Pimm, a biologist at Duke University, told Business Insider. "I can't tell you when, and I can't tell you how bad they're going to be. Some are going to be terrible, some less terrible. What we can clearly say is these trends are continuing."
In July, Pimm and several other researchers calculated in a paper that global leaders could prevent many zoonotic spillover events by spending about $20 billion per year on prevention efforts. To put that into perspective, the estimated cost of the coronavirus worldwide is $5 trillion this year, a figure that doesn't count the loss of human life.
That money, they said, should be spent in three major ways: to prevent deforestation, enforce the safe trade of wildlife, and study emerging infectious diseases that come from animals.
Fight deforestation, especially of tropical forests
Cutting down tropical forests contributes to the spread of zoonotic diseases for a couple of reasons. For one, disease-carrying mosquitoes thrive in tropical areas that have fewer trees and more puddles of water. Additionally, cutting down trees and moving people into previously forested areas puts people and wild animals into closer contact. Bats are more likely to feed near human settlements when their own habitats get disturbed, for example.
Left: Rickey Rogers/Reuters; Right: Ueslei Marcelino/Reuters
Funding programs that monitor deforestation in tropical regions and enforcing laws that penalize illegal logging could reduce deforestation by 40% in areas most likely to see virus spillover, Pimm said. That change, in turn, could lower the number of new diseases introduced into the human population.
Such programs have worked to curb deforestation before: In Brazil, incentives for preserving forests and procedures to enforce logging restrictions reduced deforestation significantly between 2005 and 2012. However, deforestation rates there are back up. In 2019, nearly 3,800 square miles of forest disappeared — an area more than twice the size of California and a 30% increase from 2018.
Create a safer legal wildlife trade, and fight the black market
It's not yet known precisely where or when the coronavirus originated in Wuhan (a wet market originally thought to be the outbreak's origin point instead was simply the site of a super-spreader event). But experts are sure that the global wildlife trade, an industry worth more than $300 billion, has contributed to multiple disease outbreaks. For example, an outbreak of monkeypox virus that sickened 47 people in 2003 was linked to pet prairie dogs brought to the US from Ghana.
Philip Wen/Reuters
Pimm and his colleagues say that such outbreaks could be prevented by funding networks like the ASEAN Wildlife Enforcement Network, which help law-enforcement agencies from different countries coordinate their responses to the wildlife black market. Enacting stricter laws could make legal wildlife trading safer, too — China was following this logic in February when it banned the consumption of terrestrial wildlife.
In their paper, Pimm's group proposed the creation of a new global agency that could monitor animals that get traded to detect emerging diseases.
Increase animal monitoring and studies of animal diseases
Studying how diseases hop from animals to humans can help scientists figure out how to address epidemics as soon as they emerge, Pimm said — and potentially prevent future ones.
However, the Trump administration in April cut government funding for a long-term project studying virus transmission between bats and humans. That research had ties to a Chinese lab falsely accused of leaking the coronavirus.
Additionally, the Trump administration cut the PREDICT program last September, which was designed to give early warnings of possible pandemics by identifying new emerging zoonotic diseases.
The US and other countries need more of these types of programs, not fewer, Pimm said.
"Americans have lost more lives to COVID than every war since World War II combined," he said. "This has had a devastating impact on our economy; there are national security issues at play here."
Pimm added that he doesn't think the Trump administration is willing to support the research necessary to protect people.
"I am desperately worried that science is now disparaged in our country," he said.
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